Welding of alitized components and an alitized component

ABSTRACT

The welding can be carried out only after the partial removal of a necessary alitized portion prior to welding an alitized component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to PCT Application No. PCT/EP2014/058064, having a filing date of Apr. 22, 2014, based off of European Application No. 13166930.1 having a filing date of May 8, 2013, the entire contents of which are hereby incorporated by reference.

FIELD OF TECHNOLOGY

The following relates to the welding of alitized components and to an alitized component.

BACKGROUND

Gas turbine components such as burner components have steels which are alitized in order to improve their corrosion properties.

Hitherto, such components were not repaired.

SUMMARY

An aspect relates to a method by means of which alitized components can be repaired or welded.

By virtue of the method features and the component features, alitized components can be welded or have an advantageous weld.

BRIEF DESCRIPTION

Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

FIG. 1 shows schematically a sequence of an embodiment of a method and an embodiment of a component.

DETAILED DESCRIPTION

A substrate 4, in particular made of a steel, very particularly made of 16Mo3, is to be welded or repaired.

In that context, alitizing (+Al) is carried out in a first step, which produces a diffusion layer 6 within the substrate 4, converting this into a modified substrate 4′, and generates a build-up layer 7.

Alitizing can also be carried out only locally.

The diffusion layer 6 preferably has a depth of 150 μm to 300 μm.

The build-up layer 7 preferably has a thickness of 100 μm.

One part of the build-up layer 7 is in particular locally removed from the surface 13 of the diffusion layer 6 such that only a remnant 7′ of the build-up layer is present, wherein the build-up layer is largely, in particular entirely, removed with respect to its thickness and thus a surface 13 of the diffusion layer 6 forms an outer surface. The local removal of the build-up layer is expedient if only part of the alitized surface of the substrate 4′ is to be welded.

In the next step, the exposed region 11 of the surface 13 is provided with a weld 10.

The procedure according to the prior art was to remove only the oxidized surface of aluminum of the build-up layer 7.

The removal of part of the build-up layer 7 can be carried out chemically and/or mechanically and/or by laser ablation.

The weld 10 can be used to weld together burner components or to build up material in order to increase wall thickness.

The repaired component has, next to one another, a substrate 4′ having a diffusion layer 6 and a weld 10 on the diffusion layer 6 together with a build-up layer 7′ on the surface 13 of the diffusion layer 6. 

1-12. (canceled)
 13. A method for repairing a component having a substrate, in which the substrate undergoes alitizing, which leads to a diffusion layer in the substrate and to a build-up layer on the diffusion layer, wherein in a next step the build-up layer is at least partially removed, and then welding is carried out in a region of the removed material of the build-up layer, in which the build-up layer is removed as far as a surface of the diffusion layer.
 14. The method as claimed in claim 13, wherein the substrate is a steel.
 15. The method as claimed in claim 13, wherein the substrate is only partially alitized.
 16. The method as claimed in claim 13, wherein, relative to a thickness of the build-up layer, only part of the thickness of the build-up layer is removed.
 17. The method as claimed in claim 13, wherein the build-up layer is removed only locally from the surface.
 18. The method as claimed in claim 13, wherein a material used for the deposition welding is steel.
 19. The method as claimed in claim 13, wherein the substrate of the component is already alitized.
 20. A component, which has an alitized substrate having a diffusion layer within the substrate, wherein there are on the diffusion layer both the build-up layer resulting from alitizing and a weld.
 21. The component as claimed in claim 20, wherein the substrate of the component is already alitized.
 22. The component as claimed in claim 20, which is a repaired component.
 23. The component as claimed in claim 20, wherein the weld is present directly on the diffusion layer.
 24. The method as claimed in claim 13, wherein the substrate is molybdenum-containing steel.
 25. The method as claimed in claim 13, wherein the substrate is made of 16Mo3.
 26. The method as claimed in claim 13, wherein the build-up layer is locally entirely removed.
 27. The method as claimed in claim 13, wherein the build-up layer is entirely removed. 